As software developers, we often work with immutable state objects in our applications to ensure data integrity and prevent unwanted mutations. However, there are times when we need to make changes to these immutable objects without compromising their immutability. This is where Immer, a popular library, comes to our rescue.

What is Immer?

Immer is a JavaScript library that simplifies the process of creating immutable updates to state objects by allowing us to write code that looks like we’re directly mutating the objects, while behind the scenes, Immer creates copies of the object with the desired changes. It provides a clean and intuitive way to work with immutable data structures.

Installing Immer

You can install Immer using npm or yarn:

npm install immer

or

yarn add immer

Basic Usage

Let’s look at an example to see how Immer can be used to modify an immutable state object:

import produce from 'immer';

// Our initial state
const state = {
  counter: 0,
  todos: []
};

// Update logic using Immer
const newState = produce(state, draft => {
  draft.counter++; // Modifying a property
  draft.todos.push('New task'); // Modifying an array
});

console.log(newState);

In the code above, we import the produce function from the immer library. We then call the produce function, passing in the original state object as the first argument and a callback function as the second argument. Inside the callback, we can modify the state object by directly mutating the draft object. Immer takes care of creating a new, immutable state object for us.

Deeply Nested Updates

Immer also handles deeply nested updates in an efficient way. Let’s take a look at an example:

const state = {
  user: {
    name: 'John',
    address: {
      city: 'San Francisco',
      state: 'California'
    }
  }
};

const newState = produce(state, draft => {
  draft.user.name = 'Jane'; // Update a nested property
  draft.user.address.city = 'New York'; // Update a deeply nested property
});

console.log(newState);

In this example, we have a nested state object with a user and address. Immer allows us to directly update the nested properties without worrying about immutability. The resulting newState object will contain the updated values.

Conclusion

Immer simplifies the process of modifying immutable state objects by providing an intuitive API that allows us to work with these objects as if they were mutable. It removes the need for manual copying and ensures the immutability of our data structures. With Immer, we can write cleaner and more readable code while maintaining the integrity of our state.

#immutable #state #Immer